(a) Field of the Invention
The present invention relates to the field of dermatology. More specifically, the present invention relates to compositions and methods for modulating hair growth.
(b) Background
Although hair growth disorders are not life threatening, their impact on social interactions and on an individual's psychological well being is undeniable. Thus, effective methods of treating hair growth disorders are greatly desired.
One of the most common hair disorders is alopecia, where humans begin losing scalp hair at the temples and on the crown of their head as they age. Although this type of hair loss is predominantly found in males, it is also present in a certain proportion of women. Alopecia can also be induced by chemical agents or physical agents (e.g., during anti-cancer chemotherapy), and the condition also results from specific disease states.
Another type of hair growth disorder results from abnormally accentuated hair growth. For example, hirsutism is manifested as excessive androgen-dependent hair growth in women, whereas hypertrichosis is an increase in androgen-independent hair growth (Bertolino et al., “Disorders of epidermal appendages and related disorders,” in Dermatology in General Medicine, 4th ed., pp. 671-695, Fitzpatrick et al., eds. (McGraw-Hill, 1993)).
A traditional treatment for alopecia is hair transplantation. This typically involves transplanting plugs of natural hair from areas of the scalp where hair is growing to bald or thinning areas of the scalp. This procedure is costly, time-consuming, painful, and does not provide a sufficient remedy in all cases. Electrical stimulus has been suggested as an alternative way to promote hair growth (see, e.g., U.S. Pat. No. 5,800,477 and references cited therein); however, such methods are of questionable efficacy.
Other methods for stimulating hair growth comprise the use of various chemicals or drugs, mud preparations, and plant extracts (see, e.g., U.S. Pat. Nos. 5,798,341, 5,767,152, 5,753,713, 5,750,107, 5,741,816, 5,739,111, 5,723,149, 5,679,378, 5,674,497, 5,663,160, 5,656,300, 5,643,898, 4,139,619, and references cited therein). There are two compounds currently in clinical use to treat alopecia: finasteride, sold as PROPECIA®, and minoxidil, marketed as ROGAINE®. A drawback of finasteride is that it can only be used by men. Furthermore, its use can result in sexual side effects such as a decreased desire for sex, difficulty in achieving erection, and a decrease in the amount of semen. Minoxidil is a vasodilatory drug which can have side effects in some patients. Similarly, mud preparations and plant extracts can produce unwelcome side effects in various patients and are of questionable efficacy. Moreover such treatments require a normal scalp with no local abrasions, dermatitis, or sunburn, rendering such methods unavailable to many individuals.
In addition to these hair growth disorders, individuals may also desire to increase, decrease, or prevent hair growth purely for cosmetic reasons. As a result, there is immense interest in the development of effective cosmetic and clinical treatments. Yet, most, if not all, of the known methods to control hair growth have several drawbacks.
For example, various procedures have been used to remove unwanted hair from the groin area, legs and face including shaving, electrolysis, use of depilatory creams, waxing, plucking and therapeutic anti-androgens, see, e.g., U.S. Pat. No. 6,093,748. However, these traditional methods have various drawbacks associated with them. For example, shaving can cause nicks, cuts and undesirable stubble. Although electrolysis keeps a treated area free of hair for prolonged periods of time, it can be expensive, painful, and may leave scarring in some cases. Depilatory creams have a high potential to irritate the skin. Waxing and plucking can cause pain, discomfort and poor removal of short hair. Finally, anti-androgens can have undesirable side effects.
Thus, alternative methods for controlling hair growth are needed.